Can the antenna length of a wireless router be increased to extend it’s wi-fi coverage? If yes , how? like say, a wire be used to increase it’s antenna length?

Dwight S

December 14, 2013 at 4:14 pm

I read that placing a metal salad bowl behind the router would increase signal strength. Like a satellite dish does.

Drsunil V

December 6, 2013 at 5:03 pm

Responses acknowledged

Matthew

December 5, 2013 at 4:50 pm

I forgot the description of the "longer" antenna - it always relates to the wavelength (which, for 2.4GHz Wifi is 12.5cm).

The most basic antenna types are the centre fed halfwave dipole (split at the centre for the feed line), or the end fed quarterwave.

Another popular arrangement, is the end fed 5/8 wave, the extra 1/8 easing the problem of feedin a dipole at the end, where the impedance is highest... why not a 3/4 wave? The extra quarter wave at the bottom operates in inverse to the halfwave above, and pushes the maximum sigan direction away from the horizontal, while the 1/8 is too small to have a difference.

To make a vertical longer, requires phasing arrangements to bring each half wave into phase with the next.
These can be quarter wave stub lines / delay sections, typically curved around the antenna or the "coaxial collinear".

A flat reflector would be metal or foil covered and placed 3cm (a quarter wave) behind the antenna - again, it would screen signal from the rear, but the increase in front signal would be less, but over a wider angle than the parabolic reflector.

All "gain" antennas work by redirecting signal from some directions to favour others, with the omnidirectional longer verticals achieving low angle gain by pancaking the pattern vertically (used with that style, a reflector should match the length of the antenna).

Other homemade types include the "cantenna" and grid antenna, while commercial directional antennas tend to of the Yagi type - either rods like a shrunken TV antenna, or loops.

Drsunil V

December 5, 2013 at 7:33 am

Thanks for a sincere attempt to provide a practical solution to the query

Matthew

November 29, 2013 at 6:35 pm

The antenna is tuned to a frequency, so just "making it longer" would take it OFF TUNE and weaken the signal, or mess up the directionality.

The most basic antenna, the quarter wave, radiates and receives in all directions around (assuming vertical) and has a vertical directionality that is from mostly horizontal (actually best is a bit above) to about 45 degrees (not much goes up).

Moving to 5/8 wave, squashes the pattern lower toward the horizontal, but with antenna gain, there is no free lunch, gain in any direction means loss in another, and the reduction in upward signal may mean poorer upstairs coverage from a router that is downstairs.

A longer antenna ether needs additional complexity to bring all section in phase, or else the directional pattern will break up into lobes and nulls. The design of antennas is quite a science, and possibly the simplest way to change is to use some form of reflector, flat, corner or parabolic

Of course you realize that extending the range of your WiFi signal will also extend the range at which wardrivers can leech off of your signal?

Guy M

November 27, 2013 at 6:38 pm

Oron nailed that. You can't really use a longer antenna on the router to increase the range. If lengthening anything to increase the range, you would want to do that on the receiver end. You may have seen WiFi cards with removable flexible antennas. You can get 'larger' antennas that will attach to the WiFi card and make your reception better.
The parabolic mirror works much like a mirror behind a candle. It doesn't make for 'more' of a signal, it just focuses it in one direction.

Drsunil V

December 5, 2013 at 7:32 am

I agree that custom-increasing wifi router antenna coverage is not practically reasonable

Jan F

November 27, 2013 at 6:36 pm

Probably not in the way you are looking for.
Of course (ab)using 1m of cable as an antenna will increase it's range but at the cost of signal quality and also transmit power. If the quality of the signal drops the network connection will drop frames and at some point render the connection useless. Also a lower transmit power will decrease the range from the "antenna" itself so the cable might cover an additional 1m but you probably lose the same or more in "over the air" distance.

To effectively increase the range you'll need a quality antenna with a higher gain than the current one. Of course this only works if your wireless device has a detachable antenna and you do have to look for the right RF connector (SMA, SMC, TNC, ...).

Also, when dealing with antennas you should inform yourself about their directional specifications.
On some occasions you might want to change an omni-directional antenna with a more directional one e.g. a Yagi antenna.

Last but not least you also have to know about wireless device. If it has more then one antenna one might be designated Rx (receiving side) and one Tx (transmitting side). In such a case you have to change both antenna equally.

Drsunil V

December 5, 2013 at 7:31 am

Thanks. I understand the custom-increasing wifi router antenna coverage is not practically reasonable

Oron J

November 27, 2013 at 6:30 pm

In short, no. In theory you could do that, but you would need a router with a detachable aerial, and you would need to extend it to exactly the right length (half the wavelength of the carrier wave). If you have such a router though, you'd be much better buying a high-gain aerial for it.

Also, you can improve directional reception by using a parabolic mirror. There are instructions on the internet on how to use a small metal bucket for the purpose, or make such a mirror out of cardboard and aluminium foil!

Drsunil V

December 5, 2013 at 7:30 am

Thanks. The parabolic mirror and the process illustrated in wikihow link by earlier respondent is same?